Replacement bed legs or bed leg castors are an attractive low profile (75mm high) option to permit easy movement of your bed. Our Wheeled Castor Furniture Legs for Beds is based on the traditional 5/16" thread size. Your bed may already have this size Insert Screw or T/Nut fitted on the underside of your bed as it has been the industry standard for many years. If not you must fit a matching 5/16" Insert Screw (available as an option) that can be retrofitted to the underside of your bed frame in place of your existing fitting. To use our Wheeled Castor Furniture Legs for Beds you must have a 5/16" thread to receive the threaded rod - no other size will suit. To fit the 5/16" Insert Screw (comes with wood thread on the outside / 5/16" metal thread on the inside) you will need a 10mm drill bit and may need to drill a new hole alongside the existing one.